To provide a data interpolation method whereby a time required for data processing and the circuit scale can effectively be reduced when a transmitter-receiver or a data recovery apparatus or the like performs waveform shaping for demodulation of a received signal.

The data interpolation method is characterized in to adopt a step wherein an interpolation filter Fb with an impulse response satisfying a Nyquist first condition is employed to separate a prescribed component with frequency band of a signal passing through a filter Fa conducting over-sampling to an input signal from a prescribed component with a frequency band of a loopback component caused by the over-sampling.